Although theory and research on schizophrenia suggest that stress contributes to its etiology, expression and course, the processes that lead from vulnerability for schizophrenia to an episode of illness remain poorly understood. Fundamental questions persist concerning the consequences of stress exposure, patient characteristics that predict sensitivity to stress, and the impact of different types of psychosocial stressors. This research draws from health psychology and developments in the basic science of emotion to address two broad goals: to specify stress and emotional reactivity in individuals vulnerable for schizophrenia, and to clarify the mechanisms that influence when and how these patients react to stress. By focusing on patients in the prodromal and first episode phases of illness, there is the opportunity to examine how stress and emotional reactivity might contribute to the onset and progression of illness and to functional outcome. Comparisons between patients across early and chronic phases of illness can provide some indication as to when some abnormalities might develop. The specific aims are to determine: the behavioral and physiological consequences of exposure to psychosocial stress in the laboratory among individuals vulnerable for schizophrenia, the relationship between the stress response and symptom onset or change during the initial course of illness, the contribution of stress reactivity to functional outcome, and the potential pathways that might account for sensitivity to perceived psychological threat by characterizing emotional reactivity and motivational state. A secondary aim is to examine the influence of various psychosocial factors on stress reactivity (e.g., life stress, coping, social support) to better understand the stress response observed in the lab. The experimental contexts will be translated from basic research and consist of a well-characterized social stressor task and various versions of the affective modulation of the startle blink reflex paradigm. In each instance, psychophysiological measures will be used to index stress, emotional reactivity and motivational state. Efforts to understand the interrelationship between schizophrenia, stress, and functional outcome are critical, as they will lead to an improved understanding of the contribution of stress to the onset and course of schizophrenia and to the development of interventions that can target areas of difficulty in work and social situations.